If you think a game should be higher or lower in ranking, then upvote or downvote it. If you don’t see a game on the list that you think should be on the list then create a top level reply with the name and system.
Spacewar, DOS, 1985
Bill Seiler! I still have a copy. Great game.
asteroids, arcade
Total Annihilation
Pokémon Crystal is just shy of your 25 year threshold depending on what month it was released (it came out in 2000 in Japan), so I’ll say Pokémon Yellow or Pokémon Gold and Silver. We can sit here and nitpick about which is the best, but Red, Blue, Yellow, Gold, Silver, and Crystal were all amazing.
Star Flight, 1986(?). Huge universe, multiple alien races, reputational, on two 360k floppy disks, and a great story too.
Wonder Boy: Monster Land, Arcade, 1987
Super Mario Bros 2, NES
sonic 3 and knuckles, Sega Genesis
IK+ (International Karate plus), Amiga, 1987
Might and Magic III
F19
B-17 (intellivision)
Pitfall
Zork
Myst
Gauntlet (arcade 4 person game)
missile command, arcade
Shinobi 3, Sega Genesis
Bubble Bobble, Arcade, 1986
Street fighter 2 - hyper fighting edition (arcade).
Played this every day after school for years as did a huge portion of my school.
Resident Evil (1996)